US7669803B2ExpiredUtilityPatentIndex 63
Optimized land mobile satellite system for north american coverage
Est. expiryDec 7, 2024(expired)· nominal 20-yr term from priority
Inventors:GOODZEIT NEIL E
B64G 1/242H04B 7/195B64G 1/1007B64G 1/1085
63
PatentIndex Score
2
Cited by
22
References
9
Claims
Abstract
A constellation, including a plurality of spacecraft, including a first, second and third spacecraft, each of the plurality of spacecraft including a broadcast capability, and each of the plurality of spacecraft in its own approximately 24-hour orbit. Each of the orbits has a substantially teardrop-shaped or oval-shaped ground track, is optimized based upon elevation angle or probability of signal availability, and has an apogee longitude of approximately 90° west to approximately 100° west. Each of the orbits has a semi-major axis of approximately 42,164 kilometers, an argument of perigee of approximately 270°, an inclination of approximately 40° to approximately 60°, and an eccentricity of approximately 0.16 to approximately 0.4. The orbits of each of the plurality of spacecraft are selected to bring each of the spacecraft to apogee at time increments of approximately eight hours.
Claims
exact text as granted — not AI-modified1. A method for determining orbits for a plurality of spacecraft in a constellation, comprising:
determining an approximately 24-hour orbit for each one of the plurality of spacecraft, the plurality of spacecraft including a first, second and third spacecraft, each of the plurality of spacecraft including a broadcast capability, wherein each of the orbits is a substantially teardrop-shaped or oval-shaped ground, and has an apogee longitude of approximately 90° west to approximately 100° west, wherein each of the orbits has a semi-major axis of approximately 42,164 kilometers, an argument of perigee ω of approximately 270°, an inclination i of approximately 40° to approximately 60°, and an eccentricity e of approximately 0.16 to approximately 0.4, and wherein the orbits of each of the plurality spacecraft are selected to bring each of said spacecraft to apogee at time increments of approximately eight hours; and
optimizing one or more of the argument of perigee, the inclination, the eccentricity, and a longitude of an ascending node L for each of the orbits by minimizing a cost function selected from the group of
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wherein 90°−min[θ i (t,e,i,L,ω)] represents maximum co-elevation angle for an i th city over a single sidereal day, N represents a number of cities, w i represents normalized city weighting factors, and P i all and P i none represent average probabilities of signal availability from the plurality of spacecraft.
2. A method for orbits for a plurality of spacecraft in a constellation, comprising:
determining an approximately 24-hour orbit for each one of the plurality of spacecraft, wherein each of the orbits has a substantially teardrop-shaped or oval-shaped ground track, is optimized based upon performance criteria, and has an apogee longitude of approximately 90° west to approximately 100° west; and
optimizing one or more of an argument of perigee ω, an orbit inclination i, an eccentricity e, and a longitude of an ascending node L for each of the orbits by minimizing a cost function selected from the group of
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wherein 90°−min[θ i (t,e,i,L,ω)] represents maximum co-elevation angle for an i th city over a single sidereal day, N represents a number of cities, w i represents normalized city weighting factors, and P i all and P i none represent average probabilities of signal availability from the plurality of spacecraft.
3. The method according to claim 2 , wherein each of said orbits has a semi-major axis of approximately 42,164 kilometers.
4. The method according to claim 2 , wherein each of said plurality of spacecraft includes a broadcast capability.
5. The method according to claim 2 , wherein the performance criteria include elevation angle from a coverage region to said plurality of spacecraft.
6. A method for determining orbits for a plurality of spacecraft in a constellation, comprising:
determining an approximately 24-hour orbit for each one of the plurality of spacecraft, the plurality of spacecraft including first and second spacecraft, wherein each of said orbits has a substantially teardrop-shaped or oval-shaped ground track, is optimized based upon performance criteria, and has an apogee longitude of approximately 90° west to approximately 100° west; and
optimizing one or more of an argument of perigee ω, an orbit inclination i, an eccentricity e, and a longitude of an ascending node L for each of the orbits by minimizing a cost function selected from the group of
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wherein 90°−min[θ i (t,e,i,L,ω)] represents maximum co-elevation angle for an i th city over a single sidereal day, N represents a number of cities, w i represents normalized city weighting factors, and P i all and P i none represent average probabilities of signal availability from the plurality of spacecraft.
7. The method according to claim 6 , wherein each of said orbits has a semi-major axis of approximately 42,164 kilometers.
8. The method according to claim 6 , wherein each of said plurality of spacecraft includes a broadcast capability.
9. The method according to claim 6 , wherein the performance criteria include elevation angle from a coverage region to said plurality of spacecraft.Cited by (0)
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